Assessing microbial stability and predicting biogas production in full-scale thermophilic dry methane fermentation of municipal solid waste.

Compared to typical anaerobic digestion processes, little is known about both sludge microbial compositions and biogas production models for full-scale dry methane fermentation treating municipal solid waste (MSW). The anaerobic sludge composed of one major hydrogenotrophic methanogen (Methanoculleus) and syntrophic acetate oxidizing bacteria (e.g., Caldicoprobacter), besides enrichment of MSW degraders such as Clostridia. The core population remained phylogenetically unchanged during the fermentation process, regardless of amounts of MSW supplied (∼35 ton/d) or biogas produced (∼12000 Nm3/d). Based on the correlations observed between feed amounts of MSW from 6 days in advance to the current day and biogas output (the strongest correlation: r = 0.77), the best multiple linear regression (MLR) model incorporating the temperature factor was developed with a good prediction for validation data (R2 = 0.975). The proposed simple MLR method with only data on the feedstock amounts will help decision-making processes to prevent low-efficient biogas production.

Prostate-specific antigen follow-up and management for patients undergoing holmium laser enucleation of the prostate.

OBJECTIVES: To investigate who needs a careful postoperative monitoring for prostate cancer (PCa) after holmium laser enucleation of the prostate (HoLEP). We examined characteristics and oncological outcomes of HoLEP-related PCa. METHODS: Patients who underwent HoLEP during 2002-2017 in a Japanese tertiary center were retrospectively analyzed. Patients were divided into non-PCa, PCa with HoLEP specimen (PCa-Ope), and PCa diagnosed during follow-up (PCa-Post). Outcomes of all HoLEP-related PCa were monitored. RESULTS: Of the total 758, 60 (7.9%) were diagnosed with PCa from resected specimen of HoLEP and 9 (1.2%) were diagnosed postoperatively. Preoperative prostate-specific antigen (iPSA), postoperative PSA (pPSA), and PSA density were significantly higher in both PCa groups than those in non-PCa group. While iPSA significantly correlated to prostate volume (PV), pPSA was not associated with PV. A receiver-operating-characteristics curve demonstrated that pPSA 1.2 ng/mL achieved the optimal cut-off (AUC 0.95) for the incidence of PCa-Post. In addition to the incidence of PCa and iPSA, lower enucleation efficiency (enucleated volume /PV) was significantly associated with pPSA >1.2 ng/mL. Among PCa-Ope, 51 were Grade Group (GG) ≤2 and 42 were followed-up with active surveillance, whereas 8 of 9 PCa-Post were GG ≥3 and 2 progressed to death. CONCLUSIONS: Patients undergoing HoLEP are associated with some risk of potential PCa. While oncological outcomes were favorable among PCa-Ope, postoperative PSA should be carefully monitored even if not diagnosed with PCa with HoLEP specimen. Enucleation efficiency should be also considered not to misread pPSA value.

Simplified capture, extraction, and amplification of cellular DNA from water samples.

DNA analysis in water samples is attracting attention in various fields. However, conventional methods for DNA analysis require a work-intensive and time-consuming sample pre-treatment. In this study, a simplified pre-treatment method for analyzing DNA in water samples was evaluated. The process consists of filtration, DNA extraction, and amplification, which can be achieved within a short time. In the filtration process, two types of filters, firstly a tissue paper (Kimwipe) and then a glass filter (GF/F), were used in sequence. The first large pore size filter enabled a reduction in filtration time by removing large particulate matter impurities present in river water matrix. Cells spiked into 1 L of river water were recovered at more than 90% within approximately 5 min filtration time. Also, DNA was extracted from the captured cells directly on the surface of the filter in only 5 min. Thus, DNA collection and extraction from a water sample can be completed within about 10 min. Furthermore, PCR amplification was performed directly from DNA-attached filter sections, which greatly reduced the number of required pre-treatment steps. Finally, we succeeded in establishing a simple and fast on-site pre-treatment system by using a hand-driven syringe filtration method. This pre-treatment system is expected to offer the possibility for the future establishment of a rapid and easy DNA analysis method applicable to various types of water samples.

Isolation and artificial production of atypical porcine pestivirus, using the swine-kidney-derived cell line SK-L.

Congenital tremor (CT) in piglets was first reported in 1922, and although the causative pathogen was unknown for many years, atypical porcine pestivirus (APPV) was recently shown to be the cause. APPV is difficult to isolate, and there have been few reports of APPV isolated from field materials. Here, we successfully isolated infectious particles from a tonsillar emulsion from a CT-affected piglet using the established swine-kidney-derived cell line SK-L. In addition, we produced APPV artificially using these cells. Thus, SK-L cells are useful for both isolation and artificial production of APPV.

Long-Term Safety, Tolerability, and Efficacy of a Transdermal Donepezil Patch in Patients with Severe Alzheimer's Disease.

BACKGROUND: Oral formulations are not suitable for demented patients with dysphagia, those refuse to take tablets, or those with drug compliance problem. However, only oral formulations of donepezil hydrochloride are approved for the treatment of severe Alzheimer's disease in Japan. OBJECTIVE: To evaluate the safety, tolerability, and efficacy of long-term application of a 55.0 mg transdermal donepezil patch switched from a 10 mg oral donepezil hydrochloride tablet, for the treatment of patients with severe Alzheimer's disease. METHODS: A 52-week, multicenter, open-label, uncontrolled (phase III) study (jRCT2080224612) was conducted in Japan between April 2019 and August 2021. A 10 mg donepezil hydrochloride tablet was administered once a day for four weeks; a 55.0 mg donepezil patch was then applied once a day for 52 weeks in patients with severe Alzheimer's disease. RESULTS: Of 64 patients received the patch, 45 completed the 52-week period. The overall discontinuation rate was 29.7% (19/64). Among the 19 patients discontinued, six patients 9.4% (6/64) discontinued due to adverse events. The incidence of adverse events at application sites was 67.2% (43/64), including application site erythema 29.7% (19/64), application site pruritus 25.0% (16/64), and contact dermatitis 20.3% (13/64). Adverse events were mild and did not increase with time, demonstrating a favorable safety profile. Cognitive function, measured using the Mini-Mental State Examination, was maintained for up to 24 weeks. CONCLUSIONS: Adverse events were considered manageable in a clinical setting. The long-term application of a 55.0 mg donepezil patch once a day was feasible treatment in patients with severe Alzheimer's disease.

Longitudinal change in castration-resistant prostate cancer biomarker AST/ALT ratio reflects tumor progression.

We investigated whether aspartate transaminase (AST)-to-alanine aminotransferase (ALT) ratio and its change during the course of treatment in castration-resistant prostate cancer (CRPC) patients is associated with tumor condition and lethality. Clinical data from 130 CRPC patients were retrospectively evaluated. AST/ALT ratios at the time of prostate cancer (PC) diagnosis, androgen deprivation therapy (ADT), CRPC diagnosis, and the final follow-up examination after CRPC treatment were calculated for each. The prognostic capabilities of the AST/ALT ratio for overall survival (OS) were analyzed by use of the Kaplan-Meier method and Cox hazard models. The median AST/ALT ratio at PC diagnosis was 1.517 and the optimal value predicting lethality defined by the receiver operating curve was 1.467. The AST/ALT ratio decreased once during ADT and then elevated in a stepwise manner with cancer progression. In surviving patients, the median AST/ALT ratio at the time of PC diagnosis was 1.423, which did not change longitudinally, whereas that in patients later deceased was significantly higher (1.620) and further elevated after CRPC diagnosis. Kaplan-Meier curves indicated significantly worse OS in patients with an AST/ALT ratio ≥ 1.467, which was confirmed by multivariate analysis. These findings indicate AST/ALT ratio as a prognostic biomarker for CRPC with longitudinal changes reflecting tumor progression.

Urine pH and imaging findings of prostate useful predictors of prolonged duration of hematospermia.

Background: Few investigations regarding hematospermia duration have been reported thus far. The aim of this study was to identify clinical factors associated with the duration of hematospermia. Methods: Clinical data of 198 patients with hematospermia treated at Toho University Omori Medical Center from 2007 to 2022 were retrospectively evaluated. To identify independent predictors of hematospermia duration, uni- and multivariate Cox analyses were performed. Receiver operating characteristic analysis, Kaplan-Meier survival curves, and propensity score matching were applied for statistical evaluations. Results: Multivariate analysis of all 198 patients showed urine pH (UpH) level and any abnormal imaging finding of the prostate to be independent predictors of hematospermia duration. Based on the receiver-operating curve of UpH level for hematospermia improvement, the patients were divided into two groups using a threshold of 6.0 (Low-UpH 5.0-6.0, n=128; High-UpH 7.0-9.0, n=70). Kaplan-Meier curves indicated that patients in the High-UpH group or with any abnormal imaging finding had a higher rate of hematospermia persistence (both P<0.05). Even after matching between the groups classified by UpH (n=60 each), multivariate analysis showed that UpH level (hazard ratio 0.75, 95% CI: 0.61-0.92; P=0.006) and any abnormal imaging finding (hazard ratio 1.55, 95% CI: 1.04-2.31; P=0.033) were independent predictors of hematospermia duration. In Kaplan-Meier analysis findings of matched cohorts, High-UpH and presence of any abnormal imaging findings remained significantly correlated with higher rate of hematospermia persistence, while further stratification using a combination of these two factors identified a stepwise reduction in that rate (P=0.019). In addition, the proportion of patients with these two factors present simultaneously was significantly higher in the group with hematospermia for two months or more, and especially with a duration of greater than six months, than in the group with a duration of less than two months. Conclusions: Although further research is needed, both UpH level and imaging findings of the prostate are considered useful biomarkers for predicting prolonged hematospermia.

Urine protein quantification in human urine on boron-doped diamond electrodes based on the electrochemical reaction of Coomassie brilliant blue.

Urinalysis is attracting interest in personal healthcare management as part of a general move to improve quality of life. Urine contains various metabolites and the protein level in urine is an indicator of kidney function. In this study, a novel electrochemical sensing system based on boron-doped diamond (BDD) electrodes was developed for the detection of protein concentrations in human urine. BDD electrodes have the advantages of a wide electrochemical potential window and low non-specific adsorption, making them ideal for simple, rapid, and compact devices for home detection of bio-relevant substances. Coomassie brilliant blue (CBB), a dye that selectively and strongly binds to urine proteins, was found to be a redox-active indicator to show a decrease in its redox currents in relation to the concentration of protein in urine samples. Our detailed studies of BDD electrodes showed their limit of detection to be 2.57 µg mL-1 and that they have a linear response that ranges from 0 to 400 µg mL-1 in urine samples. We also investigated the detection of urine protein in different urine samples. Our results agreed with those obtained using conventional colorimetric analysis. We believe this to be the first study of electrochemical detection of urine protein in urine samples on BDD electrodes, which is of great significance to be able to obtain results with electrical signals rapidly compared to conventional colorimetric analysis. This CBB-BDD technique has the potential to assist healthcare management in the form of a rapid daily diagnostic test to judge whether a more detailed examination is needed.

Efficacy and Safety of a Transdermal Donepezil Patch in Patients with Mild to Moderate Alzheimer's Disease: Open-Label, Extension Study.

BACKGROUND: In Japan, only oral formulation of donepezil hydrochloride is approved for the treatment of Alzheimer's disease. OBJECTIVE: To evaluate safety and efficacy of a donepezil patch 27.5 mg application for 52 weeks in patients with mild-to-moderate Alzheimer's disease; and to evaluate safety on switching from donepezil hydrochloride tablets. METHODS: This 28-week, open-label study (jRCT2080224517) is an extension of a 24-week double-blind (donepezil patch 27.5 mg versus donepezil hydrochloride tablet 5 mg) noninferiority study. The patch group (continuation group) continued administration of the patch and the tablet group (switch group) switched to the patch in this study. RESULTS: A total of 301 patients participated (156 patients continued using patches; 145 patients switched). Both groups showed similar course on the Alzheimer's Disease Assessment Scale-cognitive component-Japanese version (ADAS-Jcog) and ABC dementia scales. At weeks 36 and 52, changes in ADAS-Jcog from week 24 [mean (standard deviation)] were 1.4 (4.8) and 2.1 (4.9) in the continuation group, and 1.0 (4.2), and 1.6 (5.4) in the switch group. The incidence of adverse events at application site in the continuation group over 52 weeks was 56.6% (98/173). Erythema, pruritus, and contact dermatitis at application site were observed in more than 10 patients each. There was no additional adverse event of clinical concern, and no increase in their incidence from the double-blind study. During the four weeks following switching, no patient discontinued or suspended administration due to adverse events. CONCLUSION: Application of the patch for 52 weeks was well tolerated and feasible, including switching from tablets.

Combination of C-reactive protein/albumin ratio and time to castration resistance enhances prediction of prognosis for patients with metastatic castration-resistant prostate cancer.

Objective: This study aimed to identify the prediction accuracy of the combination of C-reactive protein (CRP) albumin ratio (CAR) and time to castration resistance (TTCR) for overall survival (OS) following development of metastatic castration-resistant prostate cancer (mCRPC). Methods: Clinical data from 98 mCRPC patients treated at our institution from 2009 to 2021 were retrospectively evaluated. Optimal cutoff values for CAR and TTCR to predict lethality were generated by use of a receiver operating curve and Youden's index. The Kaplan-Meier method and Cox proportional hazard regression models for OS were used to analyze the prognostic capabilities of CAR and TTCR. Multiple multivariate Cox models were then constructed based on univariate analysis and their accuracy was validated using the concordance index. Results: The optimal cutoff values for CAR at the time of mCRPC diagnosis and TTCR were 0.48 and 12 months, respectively. Kaplan-Meier curves indicated that patients with CAR >0.48 or TTCR <12 months had a significantly worse OS (both p < 0.005). Univariate analysis also identified age, hemoglobin, CRP, and performance status as candidate prognostic factors. Furthermore, a multivariate analysis model incorporating those factors and excluding CRP showed CAR and TTCR to be independent prognostic factors. This model had better prognostic accuracy as compared with that containing CRP instead of CAR. The results showed effective stratification of mCRPC patients in terms of OS based on CAR and TTCR (p < 0.0001). Conclusion: Although further investigation is required, CAR and TTCR used in combination may more accurately predict mCRPC patient prognosis.

Successful treatment of ejaculation pain with silodosin in patient with Zinner syndrome: a case report.

Background: Zinner syndrome is a rare congenital anomaly featuring a unilateral seminal vesicle cyst and ipsilateral renal agenesis. While the majority of affected patients are asymptomatic and followed with conservative management, others have symptoms such as micturition, ejaculatory difficulties, and/or pain, thus may require treatment. These patients often undergo an invasive procedure as first-line treatment, such as transurethral resection of the ejaculatory duct, or aspiration and drainage, which reduces pressure within the seminal vesicle cyst, or surgical resection of the seminal vesicle. Reported here is a patient with ejaculation pain and pelvic discomfort associated with Zinner syndrome who was successfully treated in a non-invasive manner with silodosin, an α1-adrenoceptor antagonist. Case Description: A 37-year-old Japanese male had ejaculation pain and pelvic discomfort associated with Zinner syndrome. Two months of treatment with silodosin, an α1-blocker, resulted in complete pain relief. Thereafter, conservative management with regular follow-up examinations has been conducted for five years, without recurrence of ejaculation pain or other symptoms associated with Zinner syndrome. Conclusions: This is the first known published case report of a patient with Zinner syndrome treated with silodosin who was completely relieved from ejaculation pain. The effect of α1-adrenoceptor antagonists to inhibit seminal vesicle contraction, as well as cause relaxation of smooth muscles of the urethra and prostate may contribute to reduce pain associated with ejaculation. We concluded that silodosin treatment should be attempted in affected patients before considering surgical treatment.

Efficacy and safety of a transdermal donepezil patch in patients with mild-to-moderate Alzheimer's disease: A 24-week, randomized, multicenter, double-blind, parallel group, non-inferiority study.

AIM: To assess non-inferiority of a donepezil patch 27.5 mg compared with donepezil hydrochloride tablets 5 mg in patients with mild-to-moderate Alzheimer's disease; and to compare the efficacy and safety profiles of a donepezil patch 27.5 mg with donepezil hydrochloride tablets 5 mg. METHODS: This was a 24-week, multicenter, randomized, double-blind, double-dummy, parallel group, non-inferiority (phase III) study carried out in Japan. The primary end-point was the change in the Alzheimer's Disease Assessment Scale-cognitive component-Japanese version from baseline to week 24, with the aim of evaluating the non-inferiority of the donepezil patch 27.5 mg compared with donepezil hydrochloride tablets 5 mg. RESULTS: Of 340 randomized patients, 303 completed the double-blind period. Changes from baseline in the Alzheimer's Disease Assessment Scale-cognitive component-Japanese version at week 24 (least squares mean ± standard error) were -0.7 ± 0.4 (donepezil patch 27.5 mg) and 0.2 ± 0.4 (donepezil hydrochloride tablet 5 mg). The difference in the least squares means (95% confidence interval) was -0.9 (-2.01 to 0.14). The upper bound of the 95% confidence interval for the difference between groups was less than the predefined non-inferiority margin of 2.15. The donepezil patches 27.5 mg also had a safety profile that showed good tolerability comparable with donepezil hydrochloride tablets 5 mg. CONCLUSIONS: Non-inferiority on suppression of cognitive decline was shown for the donepezil patch 27.5 mg when compared with donepezil hydrochloride tablets 5 mg in Japanese patients with mild-to-moderate Alzheimer's disease. Geriatr Gerontol Int 2023; 23: 275-281.

Effect of Conformational Variability on Seasonable Thermal Stability and Cell Entry of Omicron Variants.

The Omicron BA.1 variant of SARS-CoV-2 preferentially infects through the cathepsin-mediated endocytic pathway, but the mechanism of cell entry has not been solved yet because BA.4/5 is more fusogenic and more efficiently spread in human lung cells than BA.2. It has been unclear why the Omicron spike is inefficiently cleaved in virions compared with Delta, and how the relatively effective reproduction proceeds without the cell entry through plasma membrane fusion. Conformational variability from deep neural network-based prediction correlates well with the thermodynamic stability of variants. The difference of seasonable pandemic variants in summer and those in winter is distinguishable by this conformational stability, and the geographical optimization of variants is also traceable. Further, the predicted conformational variability maps rationalize the less efficient S1/S2 cleavage of Omicron variants and provide a valuable insight into the cell entry through the endocytic pathway. It is concluded that conformational variability prediction is able to complement transformation information on motifs in protein structures for drug discovery.

Infective endocarditis with systemic bacterial embolism caused by Staphylococcus aureus in a free-ranging Amami rabbit (Pentalagus furnessi).

The Amami rabbit (Pentalagus furnessi) is found only on the two islands of Amami-Oshima and Tokunoshima in southwest Japan. It has a primitive appearance and ecology, is an evolutionarily valuable animal and has been assigned to the International Union for Conservation of Nature Red List of Threatened Species. We describe a case with mild purulent wounds on the distal digital skin of both forelimbs and multiple nodular lesions in various organs, including the heart and kidney. Microscopically, the heart lesions were characterized by disruption of the mitral valve and multifocal myocardial necrosis and abscesses due to infection with gram-positive cocci. Similar bacterial infarctions were also found in other organs, including the kidneys. The bacteria were identified as Staphylococcus aureus by immunohistochemical and molecular biological examinations. This first report of infective endocarditis and systemic infarctions caused by S. aureus in an Amami rabbit indicates the importance of monitoring purulent injuries, even if mild, to prevent secondary infections in this species.

Establishment of guinea pig kidney cell lines with potential application in the production of a classical swine fever live GPE- vaccine.

Classical swine fever (CSF) live vaccine used in Japan, GPE- strain, is produced using guinea pig kidney (GPK)-derived primary culture cells. This means that a large number of guinea pigs are used to generate the primary GPK cells needed to produce the CSF live vaccine, and alternative solution is desired. Hence, we established two GPK cell lines capable of culturing the GPE- strain: spontaneously immortalized GPK (GPK-SI) cells were generated by repeated passaging of primary GPK cells, and the other cell line, artificially immortalized GPK (GPK-AI) cells, were obtained by introducing the SV40 large T antigen gene into primary GPK cells. Both cell lines were susceptible to the GPE- virus, and the virus grew more efficiently in GPK-SI cells at 37°C. When the culture temperature was set to 30°C, the virus titer reached 104.8 50% Tissue Culture Infectious Dose (TCID50)/mL in GPK-SI cells 7 days after virus inoculation at a multiplicity of infection (MOI) of 1, which was equivalent to that in cells cultured at 37°C. When the virus was inoculated at MOI <1, the virus titer 7 days after inoculation was higher when cultured at 30°C than when cultured at 37°C in both cell lines, reaching 105.63 TCID50/mL in GPK-SI cells. These results indicate that GPK-SI and GPK-AI cells can potentially replace primary GPK cells for the production of CSF live vaccines. This could also contribute to stable CSF vaccine production and animal welfare.

Significant inverse association of testosterone level with penile deformity severity in Japanese males with Peyronie's disease.

OBJECTIVES: We evaluated the relationship between penile curvature and testosterone in Peyronie's disease patients treated in Japan. METHODS: Data were obtained from 109 patients with Peyronie's disease treated with surgery at our hospital between April 2004 and December 2019. Penile deformity assessment was based on findings of a rigid erection induced by intracavernosal injection. Low total testosterone level was defined as <300 ng/dl. Patients were divided into two groups according to curvature severity (I, <60°; II ≥60°), then clinical factors including total testosterone were compared. Uni- and multivariate logistic regression analyses were performed to identify factors predicting severe penile deformity (≥60°). RESULTS: For all patients, mean total testosterone was 469 ng/dl and median curvature was 50°, with a significant inverse correlation found between curvature and testosterone level (p < 0.0001). Group I and II patients numbered 55 and 54, respectively. Mean total testosterone for Group II was 397 ng/dl, significantly lower than Group I (539 ng/dl). Median curvature in 15 patients with a low testosterone level was 80°, significantly higher than those with a normal testosterone range (50°). Univariable and multivariable logistic regression analysis indicated total testosterone, follicle stimulating hormone, and C-reactive protein as significant factors correlated with severe penile deformity, among which total testosterone was most relevant. CONCLUSION: The present findings confirmed that penile deformity severity is correlated with testosterone level in Japanese males with Peyronie's disease.

Colon Cancer Metastasis to the Right Testis: Case Report and Review of Literature.

Introduction: A metastatic testicular tumor is uncommon. We report here a case of testicular metastasis associated with recurrent colorectal cancer. Case Presentation. A 75-year-old male was presented with right scrotum pain one year after undergoing a right hemicolectomy combined with resection of the small intestine and omentum for ascending colon cancer (pT4N0M0). Magnetic resonance imaging of the pelvis showed a 7.3 × 5.4 × 4.5 cm mass consisting of a cystic solid tumor. A right inguinal orchiectomy was performed and right testicular pain improved after surgery. Pathology results showed that the tumor was a metastatic adenocarcinoma. The patient subsequently died two months later due to progression of the colon cancer. Conclusion: Although colorectal cancer metastasis to the testis is very uncommon, it should be kept in mind in clinical situations, especially for older males with a testicular mass or discomfort.

Parent Artery Complex Coil Protection for Side-Branched Wide-Neck Aneurysms.

This study aimed to validate the usefulness of parent artery complex coil protection for the treatment of wide-neck, side-branched, and ruptured aneurysms. A microcatheter was first introduced into the aneurysmal sac, and another microcatheter was introduced into the parent artery or near the orifice of the branch artery. A framing coil was deployed partially from the first microcatheter, and a protection coil was deployed from the second microcatheter to prevent protrusion of the first framing coil to the parent artery and side branches. After the first framing coil insertion, the protection coil was withdrawn to confirm the stability of the framing coil and blood flow. The procedures with this technique were successful for 3 patients. Parent artery complex coil protection can be an effective and safe coil embolization technique for the preservation of parent and side branch arteries and an alternative method for emergent ruptured cases.

Material-Specific Determination Based on Microscopic Observation of Single Microplastic Particles Stained with Fluorescent Dyes.

Microplastics are increasingly suspected of having serious negative effects on ecological systems and living organisms. These effects are different based on the materials of the microplastics, leading to the importance of the determination of the materials. For material determination, spectral fingerprints based on FT-IR and Raman microspectroscopy are previously and commonly used, though they require patience and special skills. In this study, we have developed a novel technique for microscopic observation of single microplastic particles stained with fluorescent dyes to enable fluorescence-based determination of materials of these particles as a first screening of material determination. Commercially available and popular microplastic particles and fluorescent dyes were used. Fluorescence microscopy was carried out to observe the degree of fluorescent intensity for various combinations of microplastics and dyes based on the difference in fluorescent intensity of microplastics before and after staining with the dyes. We have found a dependence of the fluorescent intensity on the combination of the microplastics and the dye. Fluorescein gave the highest increase in intensity for PS (polystyrene), showing a statistically significant difference between fluorescent intensity for PS and that for PP (polypropylene) or PE (polyethylene). The use of Fluorescein thus enables specific detection of PS. On the other hand, Nile Red gave the highest increase in fluorescence for PP, indicating that the combination of Nile Red and PP gives a significantly greater interaction than with other combinations. The use of Nile Red thus enables the specific detection of PP. These results indicate the possibility of the material determination of microplastics by using fluorescent dyes. This is the first demonstration of the differential determination of the materials of single-particle microplastics based on a material-specific increase in fluorescent intensity by staining microplastics with fluorescent dyes.